Voicemail (or voice mail; abbreviated v-mail or vmail) is usually a centralized system (but may be distributed) for managing telephone messages for a group of people. In its simplest form, a voicemail system mimics the functions of (and obsoletes) an answering machine, but uses one or more centralised server(s) rather than equipment at each individual telephone. Most voicemail systems are more sophisticated than answering machines, with the ability to forward messages to another voice mailbox, send messages to multiple voice mailboxes, add voice and/or other notes to a message, store messages for future delivery, make calls to a telephone or paging service when a message is received (for example as Short Message Service (SMS), Multimedia Messaging Service (MMS) or e-mail notification), transfer callers to another phone for personal assistance and play different message greetings to different callers. Voicemail messages are typically stored in a media used by computers to store other forms of data.
Many voicemail systems also offer an automated attendant facility, allowing callers answered by the system to dial a selected person's mail box or telephone. In telephony, an automated attendant system allows callers to be automatically transferred to a user's extension without the intervention of a receptionist. The automated attendant is a feature on most modern Private Branch eXchange (PBX) and key phone systems. A key phone system is a multiline telephone system typically used in small office environments.
Voicemail systems are found associated with many office telephone systems or PBX. They may also be associated with public telephone lines as network services. Mobile phones generally have voicemail as a standard network feature. Modern implementations of voicemail are or may include, for example, support fax and voicemail-to-text services, which transform each incoming voice message into text messaging for immediate delivery of a readable copy to SMS, MMS, alphanumeric pager, e-mail and so on.
Voicemail service has become a very popular telephonic service, which is rendered worldwide to millions of users of lined and wireless telephone sets. The voicemail service can either be provided locally, by the residential or enterprise voicemail system, or remotely—by the telephony or mobile service provider.
A typical voicemail system operates according to the following scheme, or according to a scheme similar to the following scheme—the calling party (the caller) dials the number of the called party. If the called party does not pick up the phone after several rings, the voicemail system plays a pre-recorded greeting message to the caller, for example “I am not available at the moment. Please leave a message”. After playing the pre-recorded greeting message, the voicemail system typically generates and forwards to the caller an audio signal (usually in the form a short beep tone) as an indication that the voicemail system has switched into a recording mode of operation, which means that the voicemail system has started recording whatever can be picked up by the telephone's microphone, whether it is the caller's spoken words and/or maybe background noises originating from various sources. Sometimes, if the caller's voice is recorded without him/her leaving discernible spoken words (for example when the caller speaks to someone nearby while keeping the telephone handset away from his mouth), the caller's voice may also be regarded as a background noise. The caller may leave a message and hang up the phone, or he/she may hang up the phone without leaving a message.
If the pre-recorded greeting message was played to the caller (meaning that the called party did not respond to the call), the voicemail system (depending on its type) may generate and forward to the called party an indication that an unheard message is believed to have been recorded. Even if inarticulate or background noise recording was provided by a caller, voicemail systems forward the caller's message regardless of content (or lack of content) to a recipient. The recipient, or called party, usually receives notifications or indications that one or more messages have been recorded for him/her. Often, the indication is a short beep tone, or a series of such beeps and/or a switched on message-waiting lamp. These indications are sent to the called party regardless of whether the caller left a message that includes discernible spoken words or not.
The called party may later retrieve the message(s), for example by dialing a special number provided by the telephony or mobile service provider. Note that in cases where the voicemail service is provided by a service provider (which is often the case) the process of retrieving the message is both time and money consuming.
Although callers are often asked to leave a message in the called party's voicemail, many people, for various reasons and unless they have to, refrain from doing so. Since callers usually do not know in advance the number of rings preceding the playing of the pre-recorded greeting message, they tend to keep the telephone line open in vain while waiting for the called party to respond. If the called party does not respond for a certain, pre-configured, time period, the voicemail system automatically switches into a record mode of operation. Therefore, even though many callers do not intend to leave a message in a voicemail system, they often accidentally trigger the recordation of blank, or spurious, messages by traditional voicemail systems, which means that called parties, unable to distinguish between legitimate and blank, or spurious, message(s), will later have to equally handle both types of messages; that is, they will have to retrieve both types of messages and only then identify and distinguish between the two types of messages. Deleting a blank message is a time and money consuming process, in addition to it being annoying, because a called party wishing to delete a blank message has to interact with a (spoken-word or key or button or other driven) menu used by the voicemail system. Of course, the more there are blank messages recorded in a voicemail, the more time recipient or receiving party would have to spend in reviewing and deleting them. Since telephone calls are usually charged per time unit, the accumulating bill involved in deleting blank messages can sometimes be significant.
Some voicemail systems try to mitigate the problem of having to deal with blank messages by asking the caller, after his message is recorded, to depress a specified key that is associated with a certain code, symbol or character, for example ‘*’, to acknowledge to the voicemail system that the caller does want to leave a message for the called party.
Voicemail systems of the types described above may reduce the number of blank messages. Such voicemail systems, however, fall short of meeting their avowed or intended goals because these types of voicemail systems require some degree of interaction with the telephone subscriber or user, usually the caller.